Infectious wads

New Delhi, March 28: Currency notes and coins in India may be ferrying potentially dangerous drug-resistant microorganisms from person to person, a study to identify microbes perched on money has suggested.

Earlier studies have detected bacteria, fungi and eggs of parasites on currency, but the study by researchers at the Kasturba Medical College (KMC) in Mangalore is the first in India to examine drug sensitivity patterns of microbes from money.

The study detected bacteria on all of 25 notes and on 24 out of 25 coins picked up from street vendors, shopkeepers, and passers-by in Mangalore.

Although the study involved only a small sample from a single city, the high level of contamination and the patterns of drug resistance observed is a cause for concern, the researchers have said in a report published recently in Current Science, a journal of the Indian Academy of Sciences.

“Finding bacteria on currency is not surprising — but the drug resistance patterns tell us how important it is to take precautions after handling money,” said Jugsharan Singh Virdi, a microbiologist at the University of Delhi who was not associated with the study.

The KMC researchers picked up coins of Re 1 and Rs 2 denomination and notes of Rs 5, Rs 10, and Rs 20, assuming that the lower the value, the more the coin or note moves from person to person.

They isolated Staphyloccocus aureus, a bacteria commonly found on the skin and in the nasal passages of healthy persons, from 11 of the currency samples.

Four of the 11 were methicillin-resistant Staphyloccocus aureus (MRSA), a strain that does not respond to many common antibiotics used to treat this infection. The organism is capable of surviving in the environment for several days.

The study also isolated from the currency samples Klebsiella and Escherichia coli — both of which have been implicated in causing illnesses in humans. Some samples appeared to have been contaminated with Enterobacter, bacteria often found in human faeces.

“MRSA, Klebsiella and E coli are of concern to even healthy persons when received in a sufficiently high dose,” said Akshay Sharma, a team member from KMC who is shortly to leave for Emory University in the US for a postdoctoral research position.

“But the other species we observed have the potential to cause harm to people with weakened immune systems — the elderly or the very young, people who regularly take steroid medications or people with active tuberculosis or with cancer,” Sharma said.

The researchers caution that their study did not quantify bacterial loads on the currency samples. “We also do not have conclusive evidence to show the transfer of bacteria from the currency to recipients,” Sharma said.

However, microbiologists say the findings highlight a potential public health hazard that has been identified earlier but has not led to any substantial changes in behaviour, particularly by medical professionals or those who handle food.

“An Indian study had identified microorganisms on currency five years ago,” said a senior microbiologist who requested anonymity. “But you can still encounter medical practitioners who handle money and then begin examining the next patient.”

“These findings hold an important public health message,” said Virdi. “It is important particularly because people often touch their faces or their noses or use spit to count currency notes,” he said.